Printed pattern and embossed pattern registration control system

ABSTRACT

A system is disclosed for securing registration of a patterned embossing roll with a similarly patterned printed moving web. The purpose of the embossing roll is to indent the surface of the printed web in register with the printing in certain designated areas. In one embodiment, a series of randomly spaced register marks on the printed web selvage edge and identically spaced register marks on the embossing roll are viewed by appropriate scanners. Electrical signatures representing the two sets of register marks are generated by the sensors and fed to a signal correlator for comparison. The correlator determines the degree of statistical error between the two signatures and displays this error in the form of a time delay on a CRT (Cathode Ray Tube). If manual registration control is desired, an operator can manually adjust the speed or phase of the embossing roll by observing the peaked wave display on the CRT to bring the roll into a statistical best fit of the embossing pattern with the printed pattern. Automatic control of embossing roll speed and orientation to achieve registration is also possible if the correlator is interfaced with a digital computer and servo correction motors on the embosser drive system. The disclosed system is an improvement over conventional benchmark oriented registration sensing and control systems in that it is capable of continuous error determinations and asynchronous error corrections on demand rather than periodically at the end of pattern length intervals.

United States Patent [191 Horst et al.

[ Oct. .28, 1975 [54] PRINTED PATTERN AND EMBOSSED PATTERN REGISTRATIONCONTROL SYSTEM [75] Inventors: Robert L. Horst; Richard M.

Ringer, both of Lancaster, Pa.

[73] Assignee: Armstrong Cork Company,

Lancaster, Pa.

22 Filed: Nov. 14, 1974 21 Appl. No.2 523,573

Related Application Data [63] Continuation-impart of Ser. No. 343,569,March 21,

1973, abandoned.

Richardson 101/181 X Primary Examiner-Edgar S. Burr AssistantExaminer-Edward M. Coven [57] ABSTRACT A system is disclosed forsecuring registration of a patterned embossing roll with a similarlypatterned printed moving web. The purpose of the embossing roll is toindent the surface of the printed web in register with the printing incertain designated areas. In one embodiment, a series of randomly spacedregister marks on the printed web selvage edge and identically spacedregister marks on the embossing roll are viewed by appropriate scanners.Electrical signatures representing the two sets of register marks aregenerated by the sensors and fed to a signal correlator for comparison.The correlator determines the degree of statistical error between thetwo signatures and displays this error in the form of a time delay on aCRT (Cathode Ray Tube). If manual registration control is desired, anoperator can manually adjust the speed or phase of the embossing roll byobserving the peaked wave display on the CRT to bring the roll into astatistical best fit of the embossing pattern with the printed pattern.Automatic control of embossing roll speed and orientation to achieveregistration is also possible if the correlator is interfaced with adigital computer and servo correction motors on the embosser drivesystem. The disclosed system is an improvement over conventionalbenchmark oriented registration sensing and control systems in that itis capable of continuous error determinations and asynchronous errorcorrections on demand rather than periodically at the end of patternlength intervals.

7 Claims, 4 Drawing Figures /|8 Traci-565k] 4 worm. H

COUNTER .ZT' COMPUTER STATISTICAL MANUAL OPERATION CORRELATOR US. PatentOct. 28, 1975 DlGlTAL COM PUTE R FEYEETRBETE. COUNTER MANUAL OPERATIONSTATISTICAL CORRELATOR CORRELATION COEFFICIENT TIME DELAY 9- PRINTEDPATTERN AND EMBOSSED PATTERN REGISTRATION CONTROL SYSTEM CROSS-REFERENCETO RELATED APPLICATION This application is a continuation-in-part ofapplicants copending application, Ser. No. 343,569, filed Mar. 21, 1973and entitled Printed Pattern and Embossed Pattern Registration ControlSystem, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention isdirected to, but not limited to, an embossing process for a patternprinted sheet and, more particularly, to a process and apparatus forsecur ing registration between a patterned embossing roll and asimilarly patterned printed web.

2. Description of the'Prior Art Current practice in automaticregistration control is summarized in a recent article entitled WebControls: The State of the Art, by Geoffrey L. Phillips, in the Gravure"magazine, Volume 17, No. 11, Nov. 1971. This article is then followed byanother article which lists various registration control systemsproduced by different companies. Current practice involves the use ofaregistration mark at a specific location of each pattern repeat or onemark for several repeats and a cycleby-cycle error detection withsubsequent pattern phase and/or repeat length corrective action.

A registration system of the conventional type is marketed by Registron,a division of Bobst Champlain, Inc., and is sold as their ModelR-500/R-425 system. The system is basically a specialized control systemfor maintaining printing registration on high-speed, multicolor webprinting and converting machines. It has also been applied to embossingtype operations. The Registron system consists of a web scanner, a phasemicrometer, a correction computer, control station and servo correctionmotor. The task of each Registron system is to detect any misregistercondition with each revolution of the printing cylinder andautomatically control a servo correction motor(s) which restores theprinting registration in a minimum time without overcorrecting. The needfor automatic registration control is created by the web and pressvariables. Variations in web characteristics such as moisture content,caliber, curl, etc. will all effect the repeat length established by thefirst printing station. In addition, variations in dryer temperature,impression pressure, infeed tension, press room 'temperature, humidity,etc. will cause repeat length changes. An accumulation of such repeatlength changes, coupled with any short-term register variables, wouldcause scrap if registration were not controlled.

In the above Registron system, the web scanner views the printed web asit passes under the scanner. As the register mark passes beneath thebeam of light that is directed on the web by the web scanner, a pulse isproduced. This pulse is compared to a cylinder reference pulse generatedby the phase micrometer. The phase micrometer is driven by the printingcylinder. The

phase micrometer has two functions. One is to produce a live electricalgate which is used to select the proper register target. The otherfunction is to produce the reference pulse as described above. Thecorrection computes the magnitude and direction of the register error.Electrical output signals are generated by the computer to drive a servocorrection motor at the proper speed in the proper direction toeliminate the misregister. The control station provides for either themanual or automatic control of both the running register and phasesetting during the normal 'press operation. The way the corrections areactually made is that the output of the computer drives a servocorrection motor at a speed proportional] to the register error, therate of register error and the press speed. As the register error isreduced towards zero, the servo correction motor runs slower and sloweruntil at zero error, the servo correction motor is stopped.

The major deficiency of the prior art structures is that register errordeterminations are made only at specific points in the pattern and,therefore, provide an indication at some single point in time toindicate a change that has occurred over a time span period. This timespan period may normally involve anywhere from 9 to 54 inches in webtravel.

SUMMARY OF THE INVENTION Unlike conventional registration systems thatprovide only periodic register error determinations, the inventiondescribed herein provides for continuous, high resolution errordeterminations. A web of material is passed through normal processingoperations until it reaches a point where it has a printed design on thesurface thereof, and it is just prior to the time that it is desirableto place an embossed pattern on the web in register with the printeddesign. Two phototransistor sensors are positioned to view two signaturetracks. Both phototransistor sensors are spaced the same distance fromthe nip of the embossing roll structure. One is positioned tocontinuously view the moving web, while the other is positioned tocontinuously view either the circumference of the embossing roll or asignature disc coupled to the embossing roll. For optimum results, boththese surfaces are provided with registration tracks. However, it isalso possible to use the actual patterns on each surface in place ofseparate, but patternrelated tracks. As the pattern track changes,reflectivity of the surface changes, and. this in turn is sensed by thephototransistor sensors. Since the printed pattern and the embossedpattern are similar, the output of both phototransistor sensors will besimilar; moreover, if the object patterns are in register, theelectrical signatures will be in time synchronization. The output fromthe two phototransistor sensors is fed to a statistical correlator whichcontinuously compares the outputs. A very high resolution of errordeviation from normal is provided by analysis in real-time of thecrosscorrelation function, and this then can be used manually orautomatically to cause a change in the speed and/or phase of theembossing roll to bring the embossing into register with the printeddesign on the web.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 of the drawing is a schematicrepresentation of the control system of the invention herein;

FIG. 2 is a showing of the selvage edge ofa sheet with register marks;

FIG. 3 is a top view of a repeat pattern and the representation of theelectronic signature of the pattern; and

FIG. 4 is a plotting of the correlation of the abovementioned electronicsignatures of the printed pattern and embossing roll.

DESCRIPTION OF THE PREFERRED EMBODIMENT The schematic representation ofthe apparatus for carrying out the invention herein is shown in thedrawing as FIG. 1. The web being processed in the apparatus of thedrawing in a conventional resilient vinyl covering material which has adesign printed on the upper surface thereof. The invention is notspecifically restricted to resilient vinyl floor covering, but could beused with any web which is moving and has a pattern printed thereon. Forexample, it could be utilized with a paper, plastic, rubber, etcv webwith a part of a design printed thereon by one station of a press and itis now desired to print additional parts of the overall design inregister with the first printing. The invention is applicable to theregistration of any two moving patterned surfaces if one can be adjustedin relationship to the other. While the invention is shown on thedrawing as an embossing roll structure, it is equally applicable toprinting structures, etc. as described above.

Web 2 is passed through its appropriate processing steps so as to haveon the upper surface thereof a printed design such as that of FIG. 3.The web moves towards an embossing roll assembly 4 which is composed ofan embossing roll 6 and a back-up roll 8. The embossing roll 6 isprovided with a pattern which is basically the same as that printed onthe web 2. It is desired to place the embossed pattern on the roll 6 inregister with the similar printed pattern on the web 2. The requiredregistration is secured by the invention herein.

Two phototransistor sensors 12 and 14 are utilized to sense the patternson the web 2 and the embossing roll 6. The patterns can be a pluralityof prior art type register marks 7 which are placed along the edge ofthe embossing roll 6 and edge (selvage) of web 2 or back of web 2) asshown in FIG. 2, or they can simply be the printed pattern and embossingroll pattern themselves as shown in FIG. 3 or a specially designedpattern track which is related to the printed pattern on the web 2. Thesame pattern of register marks or design pattern exists on both theembossing roll or an attendant device and the sheet to be embossed andthe drawing shows these patterns on the sheet only. The pattern on theembossing roll will be the same as on the sheet. The phototransistorsensors are placed the same distance from the nip of the embossing roll6 and the back-up roll 8. This distance may be a physical measurementdistance or it can be a time distance in that the sensors are positionedso that the reference marks are in a timed synchronization whereby thereference signals generated are watched at the time registration exists.For example, if the phototransistor sensor 12 scanning the web waspositioned 6 inches upstream from the nip of the embossing rollstructure4, then the second phototransistor sensor 14 would be placed 6 inchesupstream from the nip of the embossing roll structure as measured alongthe periphery of the embossing roll 6. The second phototransistor sensor14 is used to scan the pattern on the embossing roll while the firstphoto transistor sensor 12 scans the pattern on the moving web to beembossed and both patterns are the same.

The phototransistor sensor is a transistor which is sensitive tovariations in light and converts these variations into electricalimpulses. An illuminating means is designed to illuminate the areas tobe scanned. As the pattern varies, there will be a variation inreflectivity, and this in turn will result in variations in the outputsignal of the phototransistor sensor. The output of the phototransistorsensor is directly related to the variations in reflectivity of thepattern. Each pattern has its own characteristic variations. Theelectrical signals of each pattern or the electrical signature of eachpattern varies within each repeat length, but will repeat itself witheach repeat length. The signal from the register marks 7 on the edge ofthe web 2 will provide an electrical signature 9 which is basically astraight line with a series of peaks spaced as per the spacing of theregister marks (see FIG. 2). The electrical signature for the pattern asshown in FIG. 3 will be the electrical signature 11 as shown therein.

The signals from the two phototransistor sensors are then fed into adigital correlator 16. An example of one such instrument is aHewlett-Packard Model 3721A Correlator. The phototransistors 12 and 14transmit their varying output to the correlator. The correlatorcontinuously calculates and updates the crosscorrelation function of thetwo input signals. Briefly, this means that the correlator operates byrepetitively solving the standard statistical equation and continuouslydisplays on its CRT the most recent values of the correlationcoefficient as the function of the time between the two input signalsx(t) and y(t). The calculated data are available for manipulation by adigital computer and, also, are displayed on the Cathode Ray Tube (CRT)of the correlator instrument. The point of maximum correlation isindicated on the CRT plot by a maximum (or, under certain conditions, aminimum). Thus, if the pattern signature of one phototransistor sensoris in phase with the pattern signature of another phototransistorsensor, the maximum correlation coefficient is at a time delay of zero.This also means that the embossing roll pattern is going to be inregister with the printed pattern at the nip of the embossing rollstructure 4 for the case of sensors placed at equal time distances fromthe nip.

The Hewlett-Packard Model 3721A Correlator, like othercross-correlators; is provided with two input channels A and B whichreceive the signals to be statistically compared. The phototransistorsensors of this invention are connected to these channels. Thecorrelator is designed to compute the cross-correlation function of theinput data. This is the process of establishing a similarity or, inother words, determining the statistical best fit between the data beingfed into the machine. The cross-correlation function describes therelationship quantitatively and with respect to time shift betweeninputs A and B. The correlator continuously computes and displays valuesof the correlation function. The correlator is constantly receiving newinput data and the result is that the correlation function iscontinuously updated, and the statistical match between the electricalpattern signatures is known in real time period. The 100 valuesimultaneous comparison can be viewed on the CRT display which is partof the correlator and the operator may use this to manually lim rr/ makeregistration error corrections. Additionally, the Hewlett-PackardCorrelator is designed to be used with a digital computer which providesa means for further data manipulation and automatic control. TheHewlett- Packard Correlator has a program control feature, an interfaceconnection point, for permitting a computer to be interfaced with thecorrelator so that the error signal generated by the correlator, whichis in effect an electronic binary signal representing the material whichis displayed on the CRT, can be fed to a digital computer so that thedigital computer in turn can operate the necessary correction apparatusto bring the patterns into synchronization.

With a visual readout of the cross-correlation function in the form of a100 point plot on the CRT display of the correlator 16 as shown in FIG.4, it is now possible for an operator to see errors in registration andtake appropriate manual corrective action. With the correlation maximumdisplaced to the center of the CRT display by means of a time delay unit28, it has been demonstrated that an operator can adjust the objectpattern devices to be in registry to an accuracy of a few thousandths ofan inch. Normally, a zero time delay error without the time delay unit28, will put the display max imum on the left of the display screen andthis would allow errors in one direction only to be viewed for controlpurposes. In FIG. 4 peak is the time delay comparison maximum, displacedwith respect to the zero reference at the center of the display throughthe use of time delay unit 28. By manually controlling a below describeddifferential transmission in the drive train of the embossing roll, itis possible for an individual line operator to manually controlregistration by keeping the peak 15 of the display on the vertical cross17 of the CRT screen.

It is also possible to automatically control registration using theinvention herein. For the automatic mode of operation, rather than usingthe display on the CRT, the correlator will feed its output in the formof a digital data to a conventional digital computer; for example, acomputer sold under the trade name of IBM, Hewlett- Packard, etc. Thecomputer is simply hooked into the correlator at the proper computerconnection point built into the correlator and this then provides thecomputer 18 with feed-out data from the correlator. The computer 18acting upon an appropriate process algorithm and the data At it receivesfrom the correlator and the data (v) from velocity transducer 30 caninitiate corrective action f (As) to the embossing roll by I means of aservo correction motor and/or motors 20 in ,the embossing drive train.

The drive train of the embossing structure 4 can be described asfollows: A conventional drive motor 22 drives a conventional variablespeed transmission 24. The variable speed transmission in turn drivesthe back-up roll 8 and a differential draw transmission 26 which isconnected to and drives the embossing roll 6.

The differential draw transmission 26 is typically a Graham transmissionor a Fairchild Hiller Specon transmission, or the equivalent. This unithas associated with it a correction motor or motors 20 which are used toalter the output speed of the differential transmission 26 to effectregistration of the embossing roll 6 with the printed web 2. Thecorrection motor or motors 20 change the speed and/or phase of theembossing roll or computer control calculations. The correction motorsare remotely controlled by the operator through manual switches when theapparatus is in the manual mode of operation or by the computer when itis in the automatic mode of operation. Consequently, if the embossingroll 6 is out-of-register with the printed web 2, the embossing roll 6will either be speed v'aried (up or down) and/or phase shifted to bringit into register with the printed pattern. A control unit 19 operatesthe correction motors 20 and this unit may be manually or computercontrolled. If the repeat length of the printed pattern on the web isless than or more than the pattern on the embossing roll, then the speedcontrol motor is used to speed up or slow down, respectively, theembossing roll speed to shrink or stretch out the pattern being embossedto match it with the printed pattern. If the pattern length beingembossed equals the printed pattern length, but the patterns areout-of-register, i.e, out of phase, then the phase control motor isused. This causes a phase shift between the input drive and the outputdrive of the draw transmission and this in turn results in the patternsbeing placed in registry.

Therefore, this invention as described above, provides for a new andimproved method of manually or automatically controlling registration ofa pattern to be applied to a web with a pattern which has already beenapplied to the same web.

What is claimed is:

1. An apparatus for controlling the register between the pattern aboutto be placed upon a web of material and a pattern which has already beenplaced upon a web of material, said pattern being repeated on the web ata predetermined repeat length, and the pattern which is to be placedupon the web of material to be placed thereon in register with thepre-existing pattern, comprising:

a. two scanner means,

1. one scanner means scanning the pattern which exists upon the web ofmaterial,

2. said second scanner means scanning the pattern which is to be placedupon the web of material, said pattern which is about to be placed uponthe web of material being on the surface of a rotary pattern-applyingstructure,

3. both said scanners being positioned the same time distance from thepoint where the pattern applying structure engages the web of materialto apply the pattern thereon,

b. a correlator means receiving continuous electrical signature signalsfrom the two scanner means and comparing the electrical signaturesignals from the two scanner means for the best statistical match, 1.said correlator means continuously providing an indication of the phaserelationship of the signals from the two scanner means, said phaserelation ship of the signals being related to the relationship of thetwo patterns being sensed,

2. said correlation means providing an indication of any error in therelationship between the two signals from the scanner means, and

c. control means connected with the drive for the pattern-applying meansto adjust the operation of the pattern-applying means so that thepatternapplying means can be controlled to place its pattern in registerwith the pre-existing pattern on the web.

2. The apparatus of claim 1 wherein the correlation means provides asignal to a digital computer in combination with a signal from a webvelocity transducer to develop a correction signal which isautomatically fed to the control means for the pattern-applyingstructure to automatically correct the drive of the patternapplyingstructure to bring the pattern thereon in registry with the pre-existingpattern of the web of material.

3. The apparatus of claim 1 wherein the pattern on the web and on thepattern-applying structure are com posed of a main pattern and a controlpattern on the edge of the web and this control pattern is what isviewed by the scanner means.

4. The method of controlling the register between a pattern about to beplaced upon a web and a pattern which has already been placed upon theweb, said pattern being repeated on the web at a predetermined length,and the pattern which is to be placed upon the web of material to beplaced thereon in register with the pre-existing pattern, comprising thesteps of:

a. scanning by a first scanner the pattern which is to be placed uponthe web of material, said pattern is on the surface of a rotarypattern-applying means,

b. scanning by a second scanner the pattern which exists upon the web ofmaterial,

c. positioning both scanners the same time distance from the point wherethe pattern-applying means engages the web of material to apply thepattern thereon,

d. developing continuous pattern signature signals from the scanners asthey scan the patterns, said signals being indicative of the patterns,and feeding these signals to a comparison means,

e. comparing the signals from the scanners by statistical means tosecure the best statistical match there- 5. The method of claim 4wherein the signals are compared by statistical means which utilizesapproximately separate points of comparison between the patternsignatures to develop an error signal.

6. The method of claim 4 wherein there is the additional steps of:

a. developing a correction signal by relating the web velocity to theindicator of any error in the relationship between the two signals fromthe scanner, and

b. feeding the correction signal to the control drive means of thepattern-applying means to automatically correct the drive of thepattern-applying means to bring the pattern thereon in register with thepre-existing pattern of the web of material.

7. The method of claim 6 wherein the pattern on the web and on thepattern-applying structure are composed of a main pattern and a controlpattern on the edge of the web and this control pattern is viewed by thescanners.

UNITED STATES PATENT OFFICE fiETtFICATE 6F CORRECTION PATENT NO.3,915,090

DATED October 28, 1975 INVENTOR(S) Robert: L. Horst et: a].

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown beiow:

In Fig. l of the drawing, the delay signal x(f) should read gigne'd andSealed this twenty-seventh Day of April1976 [SEAL] Arrest.-

RUTH C. MASON C. MARSHALL DANN Alrc'sll'ng Officer (rmrmissimu'ruj'larems and Trademarks

1. An apparatus for controlling the register between the pattern aboutto be placed upon a web of material and a pattern which has already beenplaced upon a web of material, said pattern being repeated on the web ata predetermined repeat length, and the pattern which is to be placedupon the web of material to be placed thereon in register with thepre-existing pattern, comprising: a. two scanner means,
 1. one scannermeans scanning the pattern which exists upon the web of material, 2.said second scanner means scanning the pattern which is to be placedupon the web of material, said pattern which is about to be placed uponthe web of material being on the surface of a rotary pattern-applyingstructure,
 3. both said scanners being positioned the same time distancefrom the point where the pattern-applying structure engages the web ofmaterial to apply the pattern thereon, b. a correlator means receivingcontinuous electrical signature signals from the two scanner means andcomparing the electrical signature signals from the two scanner meansfor the best statistical match,
 1. said correlator means continuouslyproviding an indication of the phase relationship of the signals fromthe two scanner means, said phase relationship of the signals beingrelated to the relationship of the two patterns being sensed,
 2. saidcorrelation means providing an indication of any error in therelationship between the two signals from the scanner means, and c.control means connected with the drive for the patternapplying means toadjust the operation of the pattern-applying means so that thepattern-applying means can be controlled to place its pattern inregister with the pre-existing pattern on the web.
 2. The apparatus ofclaim 1 wherein the correlation means provides a signal to a digitalcomputer in combination with a signal from a web velocity transducer todevelop a correction signal which is automatically fed to the controlmeans for the pattern-applying structure to automatically correct thedrive of the pattern-applying structure to bring the pattern thereon inregistry with the pre-existing pattern of the web of material.
 2. saidcorrelation means providing an indication of any error in therelationship between the two signals from the scanner means, and c.control means connected with the drive for the pattern-applying means toadjust the operation of the pattern-applying means so that thepattern-applying means can be controlled to place its pattern inregister with the pre-existing pattern on the web.
 2. said secondscanner means scanning the pattern which is to be placed upon the web ofmaterial, said pattern which is about to be placed upon the web ofmaterial being on the surface of a rotary pattern-applying structure, 3.The apparatus of claim 1 wherein the pattern on the web and on thepattern-applying structure are composed of a main pattern and a controlpattern on the edge of the web and this control pattern is what isviewed by the scanner means.
 3. both said scanners being positioned thesame time distance from the point where the pattern-applying structureengages the web of material to apply the pattern thereon, b. acorrelator means receiving continuous electrical signature signals fromthe two scanner means and comparing the electrical signature signalsfrom the two scanner means for the best statistical match,
 4. The methodof controlling the register between a pattern about to be placed upon aweb and a pattern which has already been placed upon the web, saidpattern being repeated on the web at a predetermined length, and thepattern which is to be placed upon the web of material to be placedthereon in register with the pre-existing pattern, comprising the stepsof: a. scanning by a first scanner the pattern which is to be placedupon the web of material, said pattern is on the surface of a rotarypattern-appLying means, b. scanning by a second scanner the patternwhich exists upon the web of material, c. positioning both scanners thesame time distance from the point where the pattern-applying meansengages the web of material to apply the pattern thereon, d. developingcontinuous pattern signature signals from the scanners as they scan thepatterns, said signals being indicative of the patterns, and feedingthese signals to a comparison means, e. comparing the signals from thescanners by statistical means to secure the best statistical matchtherebetween and continuously providing an indication of the phaserelationship of the signals from the scanners, said phase relationshipof the signals being related to the relationship of the two patternsbeing scanned, f. providing an indication of any error in therelationship between the two signals from the scanners, and g.controlling the drive of the pattern-applying means to adjust theoperation of the pattern-applying means so that the pattern-applyingmeans can be controlled to place its pattern in register with thepre-existing pattern on the web.
 5. The method of claim 4 wherein thesignals are compared by statistical means which utilizes approximately100 separate points of comparison between the pattern signatures todevelop an error signal.
 6. The method of claim 4 wherein there is theadditional steps of: a. developing a correction signal by relating theweb velocity to the indicator of any error in the relationship betweenthe two signals from the scanner, and b. feeding the correction signalto the control drive means of the pattern-applying means toautomatically correct the drive of the pattern-applying means to bringthe pattern thereon in register with the pre-existing pattern of the webof material.
 7. The method of claim 6 wherein the pattern on the web andon the pattern-applying structure are composed of a main pattern and acontrol pattern on the edge of the web and this control pattern isviewed by the scanners.